For the submerged culture of tissue cells the standard stirrers and mixers used in the cultivation of microorganisms have proved to be unsuitable due to the shearing forces which were generated during their operation. Particularly when cultivating human cell lines, the strong mechanical movements lead to inadmissible damage to the cells. One has therefore carried out the exchange of nutrients and gases by the so-called airlift method whereby the aerating medium took care of the necessary mixing by means of passing through perforated plates. Also a combination of pneumatic and mechanical mixing was tried.
In particular, EP-A-0 095 804 describes a method for the submerged culture of tissue cells whereby a stirrer operating at a relatively low speed provides for a thorough mixing of nutrients and air, while a sintered plate arranged on the bottom of the container provides of the gassing. This known device is disadvantageous because the gas transfer to and from the cell is insufficent since gassing within a restricted space can take place only from the bottom of the container. The relatively slow motion of the stirrer prevents a sufficient aeration in the area of the container walls and in the upper zone of the container.